1. Field of the Invention
The present general inventive concept relates to an AC high voltage detecting device usable with an image forming apparatus using a non-contact developing method. More particularly, the present general inventive concept relates an AC high voltage detecting device which converts an AC high voltage supplied from a high voltage power supply of an image forming apparatus into a DC voltage to detect the AC voltage.
2. Description of the Related Art
An image forming apparatus prints an image corresponding to input original image data on a recording medium, such as paper. Examples of the image forming apparatus are printers, photocopiers, and facsimile machines. Laser beam printers, LED print head printers, and facsimile machines adopt an electrophotographic method to print an image. The image forming apparatus prints an image through a series of processes, i.e., charging, exposure, developing, transferring, and fixing.
FIG. 1 is a view illustrating a conventional image forming apparatus.
Referring to FIG. 1, the conventional image forming apparatus has an organic photoconductive drum (OPC) 10, a charging roller 20, a laser scanning unit (LSU) 30, a developing roller 40, a transfer roller 50, a controller 60, and a high voltage power supply (HVPS) 70.
A printing operation of the conventional image forming apparatus is performed as follows. The HVPS 70 supplies predetermined voltages to the charging roller 20, the developing roller 40, and the transfer roller 50 under the control of the controller 60. The charging roller 20 charges a surface of the OPC 10 with a charging voltage supplied from the HVPS 70.
The laser scanning unit 30 scans the OPC 10 with light corresponding to image data input from the controller 60 and thereby forms an electrostatic latent image on the surface of the OPC 10. The electrostatic latent image formed on the surface of the OPC 10 is converted into a toner image by toner supplied from the developing roller 40.
The transfer roller 50, which is driven by a transfer voltage supplied from the HVPS 70, transfers the toner image from the OPC 10 to paper. A fixing roller (not shown) fixes the toner image onto the paper with high temperature heat and pressure, and the paper is discharged from the image forming apparatus in a discharge direction. Through the above described processes, the printing operation is completed.
FIG. 2 is a view illustrating a conventional AC high voltage detecting device.
Referring to FIG. 2, the conventional AC high voltage detecting device has a high voltage power supply (HVPS) 70, a high voltage probe 81, and an oscilloscope 82.
The HVPS 70 has a pulse width modulation (PWM) input unit 71, a comparator 72, a switching unit 73, and a transformer 74. The HVPS 70 is an essential component for photocopiers, laser beam printer, and facsimile machines, as described above, and the HVPS 70 instantly converts a low voltage of 12-24V into a high voltage from several hundreds to several thousands of volts and forms a high voltage discharge on a drum of a printer or a photocopier, such that the printer can use the high voltage to print a document.
The high voltage probe 81 receives the AC high voltage from the transformer 74, converts the high voltage into a voltage that is readable by the oscilloscope 82, and outputs the converted voltage. The high voltage probe 81 reduces the received AC high voltage to a voltage approximately 1/1000 of the received AC high voltage.
However, the conventional high voltage detecting apparatus is likely to cause an error in sensing the high voltage due to an error that occurs by the oscilloscope 82 and the high voltage probe 81 when an AC voltage waveform is detected at an AC output terminal of the HVPS 70. The occurrence of the error varies setting values and thus deteriorates image quality in the image forming apparatus. Also, a time for restoring the varied setting values is additional required, which causes inefficiency of the image forming apparatus.